Modem irrigation systems, such as lawn sprinklers, often include multiple watering zones. The user typically sets an irrigation control timer to set the frequency and duration of watering for those zones. At the pre-programmed time, the system cycles through the various watering zones, sprinkling each zone for the set duration corresponding to that zone. More modern sprinkling controllers allow a user to set an initial condition of the controller where each zone can be watered for several durations during the day. So, for example, given five zones, the controller can have a first subset of durations of 20 minutes of sprinkling per zone, then another subset of durations of 15 minutes of sprinkling per zone, where the first subset of durations is followed by the second subset of durations, which is followed by a third subset, and so on.
Simple irrigation systems often waste water because the programmed watering time occurs immediately before, during or after a natural rainstorm event. More expensive systems address this problem by employing a rain sensor. After a set amount of rain has fallen, the sensor engages a switch that will prevent the timer from watering (e.g., http://www.rainbird.com/iandscape/products/controflerS/RSD.htm). U.S. Pat. No. 7,949,433 describes the use of a rain threshold to enable or disable power to an irrigation system. An interface unit is connected in series with the common line of the sprinkler activation lines. When the interface unit determines or receives an indication that a rain threshold has been exceeded and/or that other criteria have been met, the interface unit inhibits the switching device, breaking the common line. This effectively disables all electrical signals via the activation lines to the valves, until the switch is closed. In this way, the irrigation control timer 30 is not aware that the watering has been interrupted or overridden.
One significant drawback of rain sensors is that, since they have no weather prediction or forecast capability, they ignore rainfall that occurs soon (i.e., within 24-hours) after the programmed watering time. If this happens, over-watering occurs and water is wasted. The cost of water in numerous urban areas has led to more sophisticated and purportedly effective irrigation solutions, some of which take weather predictions and forecasting into account.
Another drawback of rain sensors is that they are restricted to watering only on a fixed pattern of days (usually on specific days of the week, if not every day) set by the sprinkler timer. This is inherently sub-optimal, since watering may be forced to occur shortly after a recent rain event, in order to ensure that enough watering occurs before the next allowable watering day.
U.S. Pat. No. 7,883,029 discloses an irrigation system including a radio transmitter station that transmits weather prediction information to a geographic region that includes multiple geographic sub-regions. The weather prediction information includes a respective geographic sub-region code for each of the geographic sub-regions for which a weather forecast predicts rain within a predetermined time period. An irrigation apparatus in a particular sub-region activates to water a watering zone at a schedule time. However, if the irrigation apparatus receives the sub-region code for the particular sub-region where the irrigation apparatus is located, the irrigation apparatus does not immediately activate to water the watering zone in one embodiment. The transmitter station may transmit both program content and data content on a common radio frequency signal wherein the data content includes the weather prediction information.
The use of weather information via the Internet for sprinkler control has been suggested before, as in the OpenSprinkler project: http://rayshobby.net/?page id=160 & http://rayshobby.net/blog/?p1500. Other systems take advantage of radar data. U.S. Pat. No. 6,850,819, for example, resides in an irrigation control system that comprises a meter to measure one or more weather conditions, a monitor to examine rainfall data derived from radar scanning and to extract data which is representative of the scanned rainfall; and a controller to calculate a moisture content value, a predetermined moisture content value, and regulate irrigation in accordance with the computed values.
These solutions amount to a “water, or don't water” type of operation, where if, at the time irrigation is to occur, there is rain occurring, then irrigation is prevented. However these systems fail to acknowledge that irrigation is often not needed every day, and that in many settings irrigation is only needed once every few days to ensure sufficient watering. Even in systems set up to water every few days instead of daily looking at whether it is raining or not on the day of, or at the time irrigation is to occur, leads to excess watering since rain can occur between irrigation days. Following a conventional irrigation schedule, irrigation can occur after a rain day, on a day when it is not raining. These systems fail to shift the schedule of irrigation since they only allow scheduling of irrigation to occur on specific days or at specified intervals.
Furthermore, conventional sprinkler and irrigation systems require changes in programming or operation to be made manually, at the sprinkler controller, and require being reprogrammed when special irrigation is no longer needed. For example, if new sod is put down, heavier than normal irrigation is required for one to two weeks in order to ensure the sod takes root and becomes established. After that period, the programming or control settings of the controller must be manually reverted to a normal irrigation schedule to prevent excess watering. However, in many large operations such as parks, for example, personnel can lose track of which controllers need to be changed or reprogrammed. In many cases sod may be put down in only one zone, so the extra watering is only needed in that one zone. Likewise, there can be a situation where a zone is receiving too much water. Currently, sprinkling controllers do not allow differing watering durations between zones in way that is easy to program and then revert without manually changing the setting at the controller.
Those skilled in the field of the present disclosure will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. The details of well-known elements, structure, or processes that would be necessary to practice the embodiments, and that would be well known to those of skill in the art, are not necessarily shown and should be assumed to be present unless otherwise indicated.